altering a large table

We have a large table that needs to be altered. We could either alter is by using an sql alter or we can unload the table in the revised format, drop the table, create the table in the revised format, and reload. We know the second method will work, but will be a slightly more complicated procedure. Any thoughts on the pitfalls of the first method (eg: root dbspace concerns, shared memory concerns, logging concerns, etc.) thanks, Warren J. Saccente Bellcore